I agree that OS/2 used this slogan, but several in the press, praised GeoWorks similarly. Here's a quote from an article I, Cringely wrote in December 1997...

"In the late 1980s, the company now known as Geoworks had the audacity to ship a direct competitor to Windows. Geoworks was then the name of the product and it was better than Windows, offering several powerful integrated applications.

Geoworks ran faster on an 8086 than did Windows on an 80286. Geoworks somehow pasted real multitasking on top of single-tasking DOS..."